The basic design of electric motors has remained basically the same for some period of time primarily because the electromagnetic circuitry associated with motors has largely remained the same. For salient pole motors, for example, the switched reluctance motor (SRM), the classic design has been that in which the stator windings or the excitation coils are arranged in a circular array with poles protruding inside a hollow stator core where they can interact with similar poles on the rotor. Each stator coil winding is illustrated as having a coil width Wc and a coil height Hc. A closed magnetic circuit in such motors has a flow of magnetic flux from one excited pole to another along the periphery (yoke) of the stator laminations, basically following a circumferential path to the opposing pole through the air gap and rotor.
The typical configuration for a standard SRM motor is illustrated schematically in FIG. 1(a) showing a section of an end view. In the standard configuration, if one looks at the end view of the motor, the right hand rule for flux flow dictates that flux flows in a radial direction. This arrangement has a number of limitations which affect motor performance. The flux path length follows a circular path which is not the shortest path between poles, which means that the reluctance of the machine may be higher than can be optimally obtained. The laminations needed for the stator may also be higher than can be optimally designed, thereby requiring perhaps a higher cost for more material in these laminations, and thereby increasing the overall weight of the motor and lowering its power density.